As is generally known in the art of telecommunication equipment, there has been used extensively a certain connector block with dual terminals for multiple wire conductor pairs, such as 20 conductors in 10-double pairs, referred to sometimes as a "Krone-style connector block" that provides for rapid wiring installation of key telephone systems, PBX systems, cables, and other terminal equipment. Typically, these Krone-style connector blocks are formed as a part of a modular plug connector which is fixed to a back mount frame secured to distribution frame members for distributing or cross-connecting incoming telecommunication lines.
It is also generally known that telephone communication equipment operates on relatively low voltages and is sometimes exposed to transient voltages of considerably higher levels than the normal operating voltages. For instance, this may be caused by a lightning strike, by short circuiting with a high voltage line, or by other circumstances. Therefore, the Krone-style connector blocks are designed to receive protector units with overvoltage and overcurrent protection devices so as to protect the expensive internal telecommunication equipment connected to the output side of a terminal circuit. Thus, the connector block includes a first or unprotected side for receiving connections to outside/incoming lines and a second or protected side for receiving connections to internal lines coupled to the telecommunication equipment to be protected, and terminal means so that the protector units can be plugged therein to provide the protection against overvoltage and/or over current conditions.
There exists in the prior art a number of plug-in structures for use with telecommunication connector blocks to provide connection thereto, including electrical components for protecting against overvoltage and overcurrent conditions, which appear to be best exemplified in the following U.S. Pat. Nos.: 4,171,857; 4,281,885; 4,283,103; 4,345,294; 4,410,225; 4,420,792; 4,541,682; and 4,741,711. All of these patents except for the '711 patent are assigned to Krone GmbH. The '711 patent is assigned to ADC Telecommunications, Inc.
In U.S. Pat. No. 4,281,885 issued on Aug. 4, 1981, there is shown a line communications cable end system for supporting and fixing a lead-in end and for mounting a terminal and/or isolating strips. The system includes at least one pair of spaced, parallel earthing strips 1, 1' each of which has a row of tags 1d formed integrally on the top thereof. The tags extend through the end face of a corresponding number of terminal or isolating strips 2 with LSA contacts and are lengthened so that they can contact associated equipment such as a surge diverter magazine 7.
There is taught in U.S. Pat. No. 4,345,294 issued on Aug. 17, 1982, a modular exchangeable overvoltage arrester device for terminal or junction blocks in telecommunication equipment which is adapted to accommodate a plurality of different laterally adjacent overvoltage arresters. The arrester device includes a plug-in type housing formed of a base and a removable top attached to the base. A plurality of contact blades project from the housing for making external electrical interconnections. The housing top selectively receives a plurality of different switch prongs and earth bars in order to form different versions of the housing.
In U.S. Pat. No. 4,410,225 issued on Oct. 18, 1983, there is disclosed a universal connector which includes a housing formed of two identical shell halves 2, 2a. Contact blades 3, 3a or a printed circuit board 4 are retained within the housing shell halves with the aid of various inserts 10.
In U.S. Pat. No. 4,420,792 issued on Dec. 13, 1983, there is disclosed a plug-in connector with arresters 1 for separating blocks which includes a cartridge-type housing 20 of insulating material having receptacles for the arresters 1. Each of the arresters is connected through a respective fuse element 11 and an earth contact 3 to an earth strip 7 and is exchangably retained within the receptacle by means of compression springs 10.
There is taught in U.S. Pat. No. 4,634,209 issued on Jan. 6, 1987, a modular plug connector for a multiplicity of cable conductor wires for communication apparatus which includes slide-in units 4 engagable with grooves 67 formed in modules 1, 2 and 3. The slide-in units 4 are adapted to provide a number of different functions, such as functioning either as an overvoltage protection device, an overcurrent protection device, or a thermal overload protection device.
Finally, in U.S. Pat. No. 4,741,711 issued on May 3, 1988, there is illustrated a modular distribution frame 10 which includes a modular block 20 having first and second parallel rows of wire connectors 46 with apertures 44. The wire connectors have a wire terminating end and a spring contact finger end 50. The spring contact finger end of opposing connectors extend into the apertures of a releasable electrical contact. An overload protector element 32 is provided and is adaptable for insertion into the aperture extending between opposing spring fingers so as to electrically separate the fingers. The overload protector element includes circuitry to provide electrical connection between the opposing wire connectors through the element. In FIG. 11, there is shown a schematic of the electrical components consisting of a gas overvoltage discharge element 140'; current fuses 200, 201; and bipolar Zener diodes 204, 205 so as to provide both overvoltage and overcurrent protection.
The present invention represents additional improvements over the prior art overload protectors as discussed in the aforementioned '885, '294, '225, '792, '209, and '711 patents. More specifically, the present invention provides a communication circuit protector for use with connector blocks in telecommunication equipment which includes a two-piece interfitting housing for accommodating a variety of protector circuits to provide different kinds of overvoltage and/or overcurrent protection all using the same housing. The housing is uniquely designed so as to plug-in or be inserted into the connector clips of a Krone-style connector block. Further, the side of the housing is provided with means for retaining a side ground contact which is connectible to one of the tab members in the grounding bar of the connector block.